Mixing device

ABSTRACT

A mixing device for integrating into an exhaust pipe of an internal combustion engine and for intermixing an exhaust gas flow T, which device is formed by a housing including a pipe wall for guiding the exhaust gas in a main flow direction H, an intermediate wall which at least partially delimits a flow cross section Qs of the housing, and by a mixing pipe, wherein: the mixing pipe has an injection nozzle for an additive to be incorporated, the nozzle being in the region of a first end E1 of the mixing pipe, and the mixing pipe is accommodated, in the region of a second end E2, in the intermediate wall; a perforation zone having a through-flow cross section Qp is provided at least between the injection nozzle and the intermediate wall; the intermediate wall and the mixing pipe 5 separate the housing into an inflow sector and an outflow sector; at least 90% of the gas to be guided from the inflow sector to the outflow sector can be directed through the perforation zone; a wedge-shaped flow-directing element having a directing nose is provided after the mixing pipe, which nose protrudes beyond the pipe wall and/or the intermediate wall and by means of which the exhaust gas flow T can be divided into two partial flows T1, T2; and wherein the partial flows T1, T2 can be brought into a counter swirl flow in relation to the main flow direction H.

FIELD OF THE INVENTION

The invention relates to a mixing device for integrating into an exhaustpipe of an internal combustion engine and for intermixing an exhaust gasflow T, which device is formed by a housing comprising a pipe wall forguiding the exhaust gas in a main flow direction H and an intermediatewall which at least partially delimits a flow cross section Qs of thehousing and by a mixing pipe, wherein the mixing pipe has an injectionnozzle for an additive to be incorporated, the nozzle being in theregion of a first end E1 of said mixing pipe, and the mixing pipe isaccommodated in the region of a second end E2 in the intermediate wall,wherein a perforation zone having a through-flow cross-section Qp isprovided at least between the injection nozzle and the intermediatewall, wherein the intermediate wall and the mixing pipe separate thehousing into an inflow sector and an outflow sector, wherein at least90% of the gas to be guided from the inflow sector to the outflow sectorcan be directed through the perforation zone.

BACKGROUND OF THE INVENTION

A mixing device is already known from U.S. Pat. No. 8,033,104 B2 forconnecting an exhaust pipe of an internal combustion engine for mixingan exhaust gas flow. Said device has an intermediate wall on which acylindrical mixing pipe with an injection nozzle opens out on the endside. The exhaust gas flow enters on the luff side of the intermediatewall through the perforation into the mixing pipe, and leaves the mixingpipe opposite the injection nozzle on the lee side of the intermediatewall.

Further, a mixing device for connecting an exhaust pipe of an internalcombustion engine for mixing an exhaust gas flow is known from US2010/0263359 A1. Said device has a cylindrical mixing pipe with aninjection nozzle and with a perforation, which blocks the exhaust pipein the manner of an intermediate wall up to the perforation. The exhaustgas flow enters on the luff side of the perforation into the mixingpipe, and leaves the mixing pipe opposite the injection nozzle on thelee side.

A mixing pipe for integration into an exhaust pipe is known from US2015/0040537 A1, wherein the mixing pipe has a cylindrical section andconical section connected to this. In both sections, different recessesand openings are provided, through which the exhaust gas flows into themixing pipe.

SUMMARY OF THE INVENTION

The object of the invention is to design and arrange a mixing devicesuch that an improved mixing behavior is guaranteed.

The object is attained by means of the fact that after the mixing pipe,a wedge-shaped flow directing element is provided with a directing nosewhich protrudes over the tube wall and/or the intermediate wall, and bymeans of which the exhaust gas flow T can be divided into two partialflows T1, T2, wherein the partial flows T1, T2 can be brought into acounter swirl in relation to the main flow direction. Here, a firstpartial flow T1 is deflected in a counter-clockwise direction and asecond partial flow T2 is deflected in a clockwise direction, so that animproved mixing of the exhaust gas flow with the additive and animproved feed flow into a downstream substrate such as a catalyzer orparticle filter are achieved.

In this regard, it can be advantageous when the mixing pipe has an ovalprofile form F with a height h running along a main axis and with abreadth b running along an auxiliary axis, wherein the main axis isaligned transverse to the main flow direction H of the exhaust gas flow,with h>=1.2 b. The approach flow and inflow into the mixing pipe isimproved through the use of the broader approach flow area. With theexception of smaller rinsing openings within the intermediate wall,preferably close to the housing wall, the entire exhaust gas flow mustbe guided through the mixing pipe.

Additionally, it can be advantageous when the following applies for thethrough-flow cross section Qp of the perforation zone in relation to theflow cross section Qs of the housing: 0.05 Qs<=Qp<=0.6 Qs or 0.07Qs<=Qp<=0.5 Qs or 0.08 Qs<=Qp<=0.45 Qs. Thus, the standards for minimalflow losses on the one hand and for an advantageous acceleration andmixing of the exhaust gas flow on the other are met.

The object is also attained by means of an exhaust pipe with anintegrated mixing device and an exhaust gas system with such an exhaustpipe.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and details of the invention are explained in thepatent claims and in the description, and illustrated in the figures, inwhich:

FIG. 1 shows a side view of the mixing device with opened housing 2;

FIG. 2 shows a profile view A-A according to FIG. 1;

FIG. 3 shows a principle sketch of the mixing pipe from above.

DETAILED DESCRIPTION OF THE INVENTION

A mixing device 1 shown in FIG. 1 has a housing 2 with a pipe wall 2.1,within which a mixing pipe 5 and a flow-directing element 6 arearranged. The housing 2 has an integral pipe adapter 2.4 in the area ofthe entrance opening, via which it is connected to an exhaust pipe 4.1of an exhaust gas system, not shown. Also, the housing 2 is connected inthe area of the outlet opening to an exhaust gas follow-up treatmenthousing 4.2, not presented in greater detail, of an exhaust gastreatment element.

An exhaust gas flow T flows via the exhaust pipe 4.1 in a main flowdirection H into the mixing device 1 or the housing 2 and leaves saidhousing on the end side in order to flow out into the additional exhaustgas treatment housing 4.2.

A mixing pipe 5 is provided within the housing 2, which protrudes in aradial direction into the housing 2 in relation to the main flowdirection H. An intermediate wall 3 adjoins the mixing pipe 5, whichpartially closes a flow cross section Qs of the housing 2. The exhaustgas flow T, which arrives at the luff side 3.1 of the intermediate wall3 and at the mixing pipe 5, thus enters the mixing pipe 5 via aperforation zone 5.2 of the mixing pipe 5, and exits the mixing pipe 5on the end side on the mixing pipe 5 (shown here towards the top). On alee side 3.2 of the intermediate wall 3, a flow directing element 6 islocated, via which the exhaust gas flow T exiting from the mixing pipe 5is divided into two partial flows T1, T2.

In the profile view A-A shown in FIG. 2, it is demonstrated that theflow directing element 6 has a directing nose 6.1 which (here from thetop) enters into the flow chamber in a radial direction to the housing 2and generates a partial flow T1 running in a clockwise direction and apartial flow T2 of the exhaust gas flow running in an anti-clockwisedirection. The flow directing element 6 is supplemented by a directingbody 6.2 which is arranged opposite to the directing nose 6.1 inrelation to the exhaust gas flow (here in the lower area), and to thisextent limits the kidney-shaped directing channel of the mixing device1. The intermediate wall 3 is an integral component of the flowdirecting element 6 in the lower area.

The exhaust gas flow T thus enters into the additional exhaust gasfollow-up treatment housing 4.2 in two partial flows T1, T2 oriented inopposite directions.

Opposite an exit end or a second end E2 of the mixing pipe 5, aninjection nozzle 5.1 is provided in the area of a first end E1, throughwhich the additive is entered into the interior of the mixing pipe 5 forthe purpose of retention through the exhaust gas flow T.

According to FIG. 3, the mixing pipe 5 has an oval profile, so that amedium inflow angle between the exhaust gas flow T and its main flowdirection H and the mixing pipe wall with respect to the luff side ofthe mixing pipe 5 increases to approximately 90°. The mixing pipe 5 herehas a ratio between the height h and the breadth b of approximately 1:4.

LIST OF REFERENCE NUMERALS

-   1 Mixing device-   2 Housing-   2.1 Pipe wall-   2.2 Inflow sector-   2.3 Outflow sector-   2.4 Pipe adapter-   3 Intermediate wall-   3.1 Luff side-   3.2 Lee side-   4.1 Exhaust gas pipe-   4.2 Exhaust gas pipe, exhaust gas follow-up treatment housing-   5 Mixing pipe-   5.1 Injection nozzle-   5.2 Perforation zone-   5.3 Main axis-   5.4 Auxiliary axis-   6 Flow directing element-   6.1 Directing nose-   6.2 Directing body-   b Breadth of 5-   E1 First end-   E2 Second end-   F Profile form of 5-   H Main flow direction-   h Height of 5-   Qp 5.2-   Qs Through-flow cross section 2-   T Exhaust gas flow-   T1 Partial exhaust gas flow-   T2 Partial exhaust gas flow

What is claimed is:
 1. A mixing device for integrating into an exhaustpipe of an internal combustion engine and for intermixing an exhaust gasflow T, comprising: a housing comprising a pipe wall for guiding theexhaust gas in a main flow direction H and an intermediate wall which atleast partially delimits a flow cross section Qs of the housing and by amixing pipe, wherein the mixing pipe has an injection nozzle for anadditive to be incorporated in the region of a first end, and isaccommodated in the region of a second end in the intermediate wall,wherein a perforation zone having a through-flow cross-section Qp isprovided at least between the injection nozzle and the intermediatewall, wherein the intermediate wall and the mixing pipe separate thehousing into an inflow sector and an outflow sector, wherein at least90% of the gas to be guided from the inflow sector to the outflow sectorcan be directed through the perforation zone, wherein after the mixingpipe, a wedge-shaped flow directing element is provided with a directingnose which protrudes over the pipe wall and/or the intermediate wall,and by means of which the exhaust gas flow T can be divided into twopartial flows T1, T2, wherein the partial flows T1, T2 can be broughtinto a counter swirl in relation to the main flow direction H.
 2. Themixing device according to claim 1, wherein the mixing tube has an ovalprofile form F with a height h running along a main axis and a breadth brunning along an auxiliary axis wherein the main axis is alignedtransverse to the main flow direction H of the exhaust gas flow, withh>=1.2 b.
 3. The mixing device according to claim 2, wherein thefollowing applies to the through-flow cross section Qp of theperforation zone in relation to the flow cross section Qs of thehousing:0. 05 Qs<=Qp<=0.6 Qs or 0.07 Qs<=Qp<=0.5 Qs or 0.08 Qs<=Qp<=0.45 Qs. 4.An exhaust pipe with an integrated mixing device according to claim 1.5. An exhaust system with an exhaust pipe according to claim
 4. 6. Anexhaust pipe with an integrated mixing device according to claim
 2. 7.An exhaust pipe with an integrated mixing device according to claim 3.8. An exhaust system with an exhaust pipe according to claim 7.